When spheres are packed together so that they take a minimum amount of space, they will form a regular structure in which every sphere abuts exactly 12 "neighbors". Here is how any one of these spheres (shown in white) sees its 12 neighbors (shown in bronze): Instructions: Drag mouse to rotate view; Use ← and → keys to change sphere sizes; Use ↑ and ↓ keys to change view distance; Use space bar to hide or show links.